NADPH diaphorase activity and nitric oxide synthase immunoreactivity in lordosis-relevant neurons of the ventromedial hypothalamus.

The distribution of the enzymes NADPH diaphorase and nitric oxide synthase in the ventromedial nucleus of the hypothalamus of cycling and ovariectomized/estrogen-treated and control female rats was demonstrated using histochemical and immunocytochemical methods. Serial section analysis of vibratome sections through the entire ventromedial nucleus showed that NADPH diaphorase cellular staining was localized primarily in the ventrolateral subdivision. NADPH diaphorase staining was visible in both neuronal perikarya and processes. Light microscopic immunocytochemistry using affinity-purified polyclonal antibodies to brain nitric oxide synthase revealed a similar pattern of labelling within the ventromedial nucleus and within neurons of the ventrolateral subdivision of the ventromedial nucleus. Control experiments involved omitting the primary antibodies; no labelling was visible under these conditions. Some, but not all, neurons in the ventrolateral subdivision of the ventromedial nucleus contained both NADPH diaphorase and brain nitric oxide synthase as demonstrated by co-localization of these two enzymes in individual cells of this area. That NADPH diaphorase and brain nitric oxide synthase were found in estrogen-binding cells was shown by co-localization of NADPH diaphorase and estrogen receptor and brain nitric oxide synthase and estrogen receptor at the light and ultrastructural levels, respectively. Our studies suggest that brain nitric oxide synthase is present and may be subject to estrogenic influences in lordosis-relevant neurons in the ventrolateral subdivision of the ventromedial nucleus. The hypothalamus is a primary subcortical regulatory center controlling sympathetic function. Therefore, not only is nitric oxide likely to be important for reproductive behavior, but also for the regulation of responses to emotional stress and other autonomic functions.

gamma-Aminobutyric acid and somatostatin immunoreactivity in the visual cortex of normal and dark-reared rats.

Our previous single unit and ultrastructural studies of visual cortex of dark-reared rats revealed an impairment of intracortical inhibitory mechanisms [2,3,5]. Neurochemical changes in inhibitory neurotransmitter and/or neuropeptides, such as gamma-aminobutyric acid (GABA) and somatostatin (SS), respectively, may contribute to the observed alterations. The present study was designed to measure GABA and SS alterations in the visual cortex of the same dark-reared preparation, as possible neurochemical correlates of the changes seen both physiologically and anatomically in previous companion studies. In the present investigation the mean densities of GABA- and SS-immunoreactive neurons in area 17 of dark-reared rats were determined and compared to the density of those of rats reared in normal lighting conditions. Dark-rearing resulted in a significant decrease in the density of GABA-immunoreactive neurons in all cell layers of area 17 of the rat visual cortex; not limited to the thalamorecipient layer(s). There was also a higher mean density of total cortical cells in dark-reared animals. No differences, however, were seen in the density of SS-immunoreactive neurons. The alterations of GABA-immunoreactive neurons in all cortical layers agree with the altered synaptic ultrastructure and physiological responses seen in all cortical layers as reported in our previous companion studies. Taken together, these studies further support the notion of a deficit in intracortical inhibitory mechanisms in the visual cortex of dark-reared adult rats.

Bilirubin production after supplemental oral vitamin E therapy in preterm infants.

The purpose of this investigation was to determine the influence of early vitamin E supplementation on the rate of heme catabolism (bilirubin production) in healthy preterm infants. Bilirubin production was estimated from the concentration of carbon monoxide in "end-tidal" gas. Serum vitamin E, hemoglobin, and bilirubin levels were determined by standard techniques. Thirty infants received supplementation with vitamin E or placebo in a double-blind, randomized fashion. Infants were studied on day 1 of life prior to therapy, and on days 3 and 7 postnatally. Results showed that in both placebo-supplemented and vitamin E-supplemented groups, vitamin E levels were significantly higher on days 3 and 7 compared with day 1. Bilirubin production was not significantly different on day 3 compared with day 1 in either group, but was significantly lower in both groups by day 7 compared with day 1. There were no significant differences in hemoglobin and serum bilirubin levels between the two groups at any point in time. In conclusion, although vitamin E supplementation significantly raises vitamin E levels, placebo-supplemented premature infants also achieve vitamin E sufficiency and a decrease in bilirubin production by day 7 of age.

Pulmonary excretion rates of carbon monoxide using a modified technique: differences between premature and full-term infants.

The pathophysiology of the exaggerated hyperbilirubinemia in premature infants remains unclear. The relative contribution of bilirubin production may be estimated by measuring the pulmonary excretion rate of carbon monoxide (VeCO). We found that the mean VeCO of premature infants, 16.7 +/- 5.0 microliters/kg/h, was significantly elevated (p less than 0.05) compared with the mean VeCO of full-term infants, 13.9 +/- 3.5 microliters/kg/h. Premature infants who required phototherapy had a significantly (p less than 0.05) higher mean VeCO than those who did not. The VeCO did not correlate with gestational age, implying that factors which associate frequently but variably with gestational age may have an important influence on heme catabolism.

Ultrastructure of neurons in the ventromedial nucleus or the hypothalamus in ovariectomized rats with or without estrogen treatment.

The fine structure of the ventrolateral and dorsomedial subdivisions of the ventromedial nucleus (VMN) of the hypothalamus was examined in ovariectomized/control and ovariectomized/estrogen-treated rats to compare neurons of these areas to other neurons (specifically the ventrolateral thalamus), and to determine the effects of estrogen on these cells. The neurons of the VMN contain a large nucleus with a prominent nucleolus, rough endoplasmic reticulum (RER), polysomes, a Golgi complex, coated, uncoated and dense-cored vesicles, lysosome-like bodies, inclusion bodies, multivesicular bodies whorl bodies and myelin figures. Similar organelles were present in the neurons of the ventrolateral thalamus, although polysomes wee more prominent, and the cells lacked dense-cored vesicles in the perikarya. Differences in the cells of the VMN between ovariectomized/control and ovariectomized/estrogen-treated rats included a more conspicuous stacking of the RER and greater number of dense-cored vesicles in the estrogen-treated group in both the ventrolateral and dorsomedial subdivisions. In both areas the differences were statistically significant, although more marked in the ventrolateral subdivision. In both VMN subdivisions, the increased stacking of the RER could be correlated with the greater number of dense-cored vesicles and may reflect increased biosynthesis of a secretory product.